The main characteristics, problems, and prospects for Western European coastal seas

Located to the far West of Western Europe, France has a western maritime coastal zone of more than 3800 km, which is widely influenced by the North-eastern Atlantic. The English Channel, an epi-continental shallow sea with very strong tides, runs along 650 km of the French coast and 1100 km of the English coast. It is also a bio-geographical crossroad encompassing a much wider range of ecological conditions than other European seas. France's Atlantic coast north of the Gironde estuary is a succession of rocky and sandy shorelines, including a sizeable intertidal zone, a wide continental shelf, and two major estuaries (Loire and Gironde). South of the Gironde, the 260 km of coastline is low, sandy and straight, with a narrowing continental shelf further on South due to the presence of the Cape Breton canyon in the bathyal and abyssal zones. Interface between the continental and oceanic systems, these bordering seas--North Sea, English Channel and Atlantic Ocean--have been the subject of many recent research programmes (the European Mast-FLUXMANCHE and INTERREG programmes; the national coastal environment programme and the LITEAU programme in France), designed to improve comprehension of the functions, production, and dynamics of these seas as well as their future evolution. Given the many conflicting practices in these littoral zones, integrated coastal zone management appears to be essential in order to cope with both natural phenomena, such as the infilling of estuarine zones, cliff erosion, and rising sea levels, and chronic anthropogenic pressures, such as new harbour installations (container dikes, marinas), sea aggregate extraction for human constructions, and offshore wind mill farms. This article provides as complete an overview as possible of the research projects on these bordering seas, both those that have recently been accomplished and those that are currently in progress, in order to highlight the main characteristics of these ecosystems and to underline the future challenges for European marine research in terms of the integrated coastal zone management of these highly significant coastal zones.     

有关深部地幔的两种观点

地核－地幔边界层（即在液态金属的外核与固态富含二氧化硅的地幔之间的分界面）无论是在地震波的波速上还是在地球内部的密度上都表现出极大的反差。确定接近这一边界层的地幔性质的过程就是向我们有关地球的演化和对其当今的动力学特性的理解提出挑战的过程。不久前,对在最下层地幔中波速的三维（３Ｄ）变化的性质和原因还有两种观点。第一种观点认为是由于在地核－地幔边界层之上数百公里处由于地形的剧烈起伏而造成波速的尖锐突变。而第二种观点则认为是在下地幔中大尺度的不均匀造成了径向上的波速梯度。前一种观点意指存在着一个化学…     

The 825-1110 angstroms EUV spectrum of Venus

On 15 August 1994 we launched the EUVS sounding rocket payload to observe the 825-1110 angstrom region of Venus's far ultraviolet airglow spectrum. The EUVS telescope/spectrograph obtained good data at five times higher spectral resolution than was previously available in the far ultraviolet. We present these data and compare our results to those obtained by the Galileo UVS and Venera 11/12 UV spectrophotometers. We identify several new spectral emission features, including both singly ionized nitrogen and molecular nitrogen in Venus's spectrum. We also see evidence for electron-impact-induced emission from CO. Finally, the EUVS data indicate that the "Ar" emissions detected in Venus's far ultraviolet spectrum by Venera 11/12 spectrophotometers are in fact not due to argon, thus eliminating the discrepancy between in situ and remote sensing measurements.     

Homochirality as the signature of life: the SETH Cigar

A characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. It is therefore suggested that a search for extra-terrestrial life can be approached as a Search for Extra-Terrestrial Homochirality (SETH). A novel miniaturized space polarimeter, called the SETH Cigar, is described which could he used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. It is believed that homochirality will be found in the subsurface layers on Mars as a relic of extinct life.     

南极构造——ERS—1卫星测得的海洋重力场及其对构造的制约

在西南极洲附近,从Ｒｏｓｓ海东部直到Ｗｅｄｄｅｌｌ海,对这一片冰覆盖的大洋和制图学了解甚少的区域,已通过包括ＥＲＳ－１大地测量和波形数据等的卫星测高方法,获得了高解象的重力场,这一重力场展现了该区整个构造的结构,如代表由早期（６５～８３Ｍａ前）太平洋－南极海底扩张而留下的断裂带的重力构造线,这一扩张将Ｃａｍｐｂｅｌｌ高原和新西兰大陆从西南极洲分离出来,这些构造线制约了板块运动的历史,证实了下述假设